Disk drives typically include a spindle motor for rotating one or more disks in order to read data from and write data to surfaces of the disks. The spindle motor includes a stator having a plurality of coils, and a rotor having one or more rotor magnets and a rotating motor hub on which the disks may be mounted and clamped. Different coils of the stator are alternately energized to form a changing electromagnetic field that pulls/pushes the rotor magnets, thereby rotating the motor hub. Rotation of the motor hub, in turn, results in rotation of the disks mounted thereto.
Although the motor hub and disks are typically balanced during the disk drive manufacturing process, the spindle motor often emits vibrations during operation of the disk drive due to slight imbalances in the motor itself or in the disk pack. Such imbalances are nearly impossible to completely eliminate, and become even more pronounced at the high rotational velocities reached by higher performance disk drives. The vibrations emitted by the spindle motor can degrade servo performance and can lead to undesirable vibration levels emitted by the disk drive.
There is therefore a need for a disk drive that causes less vibration.